Deodorant material and process for producing the same

ABSTRACT

The invention provides a deodorizing article which can be used semi-permanently and maintains sufficient mechanical strength under usual conditions of use and a method for producing the deodorizing article. The deodorizing article of the invention is produced by dispersing in a medium a clay mineral having meso-pores, gypsum series, a mineral having a pore size greater than that of the gypsum series, and a white inorganic filler, and molding the formed dispersion.

TECHNICAL FIELD

The present invention relates to a deodorizing article which can be usedsemi-permanently, and more particularly to a deodorizing article whicheffectively removes an oil-related odor generated from a kitchen. Theinvention also relates to a method for producing the deodorizingarticle.

BACKGROUND ART

Conventionally, there have been known methods for removing offensiveodor substances from a variety of sources of offensive odor; e.g., adeodorization method by adsorption; a chemical deodorization methodincluding neutralization and decomposition of an odorous substance byuse of a chemical; and a biological deodorization method includingdecomposition of an odor component by use of a microorganism.

Generally, the adsorption deodorization method employs activated carbon.After the activated carbon has been used for a certain period of time,the effect of activated carbon weakens considerably to such a level thatsubstantially no deodorization is expected. Therefore, the deodorizingmaterial must be replaced by new material at predetermined intervals,which is cumbersome.

A problem arises upon employment of the chemical deodorization method.Specifically, the method requires direct contact between an odoroussubstance and a chemical for causing chemical reaction. Thus, such achemical requires additional care such as periodical replacement orreplenishment, and handling of chemicals involves hazard. This situationis also problematic.

The biological deodorization method is less hazardous. However, themethod also involves problems such as requiring a large deodorizationfacility and a water-supply facility.

These conventional methods require maintenance work such asreplacement/replenishment of material or supply of water. In the eventof failure to perform the maintenance, the article and method employedfor deodorization fail to function. In other words, a offensive odorcannot be removed even though the deodorizing article is employed incombination with the deodorizing method.

In order to solve the aforementioned problems, the present applicantpreviously filed an application (Japanese Patent Application Laid-Open(kokai) No. 2002-095730) directed to a semi-permanently usabledeodorizing article developed by the applicant. The previous inventionhad been accomplished on the basis of the inventors' finding that adeodorizing article formed by dispersing in gypsum series a clay mineralhaving a tunnel-like micro-structure (e.g., sepiolite or palygorskite),which mineral generally has one-dimensional tunnel pores (i.e.,micro-pores) and meso-pores, exerts a semi-permanent deodorizationeffect on the basis of adsorption and desorption of an odor substance,in cooperation with the moisture-maintenance effect of the gypsumseries. More specifically, in the city of Tokyo, the odor concentrationof exhaust from kitchens of restaurants and other food businesses isrestricted to fall under a regulation standard in accordance with theTokyo Metropolitan Environmental Pollution Ordinance. Under thesecircumstances, although pursuing a deodorizing article which attainscomplete deodorization may have some meaning, from a viewpoint thattakes into consideration use of the article involving the aforementionedmaintenance, a deodorizing article which can suppress the odorconcentration to a level below regulation standard determined by, forexample, ordinances or to a level below a certain concentration (e.g., alow odor concentration where an offensive odor is not sensed) and whichcan be used semi-permanently could be more effective. The previousinventors have considered this viewpoint.

However, poor mechanical strength of the deodorizing article raises theproblem that the deodorizing article is readily damaged (e.g., broken)during an actual installation operation.

DISCLOSURE OF THE INVENTION

In view of the foregoing, an object of the present invention is toprovide a deodorizing article which can be used semi-permanently andmaintains sufficient mechanical strength under usual conditions of use.Another object of the invention is to provide a method for producing thedeodorizing article.

In order to solve the aforementioned problems, a first mode of thepresent invention is drawn to a deodorizing article, characterized inthat the deodorizing article is produced by dispersing in a medium aclay mineral having meso-pores, gypsum series, a mineral having a poresize greater than that of the gypsum series, and a white inorganicfiller, and molding the formed dispersion.

According to the first mode, mechanical strength of the article isenhanced by the white inorganic filler while a semi-permanentdeodorization effect is maintained, the effect being exerted by themeso-pores of the clay mineral on the basis of adsorption and desorptionof an odor substance, in cooperation with the moisture-maintenanceeffect of the gypsum series.

A second mode of the present invention is drawn to a specific embodimentof the deodorizing article of the first mode, which further contains afinely divided powder of a clay mineral having meso-pores.

According to the second mode, a state in which each raw material isuniformly dispersed is consistently attained, thereby producingdeodorizing articles having no variation in performance.

A third mode of the present invention is drawn to a specific embodimentof the deodorizing article of the first or second mode, which has abending strength of 0.49 MPa or higher.

According to the third mode, the deodorizing article has such amechanical strength that will not permit collapsing of the articleduring manual handling.

A fourth mode of the present invention is drawn to a specific embodimentof the deodorizing article of any of the first to third modes, whereinthe clay mineral is at least one species selected from sepiolite andpalygorskite, and the mineral having a pore size greater than that ofthe gypsum series is expanded perlite.

According to the fourth mode, the meso-pores of sepiolite orpalygorskite exert a semi-permanent deodorization effect on the basis ofadsorption and desorption of an odor substance, in cooperation with themoisture-maintenance effect of the gypsum series, and desorption ofsubstances which have been adsorbed by the clay mineral is promoted bythe presence of macro-pores of expanded perlite.

A fifth mode of the present invention is drawn to a specific embodimentof the deodorizing article of any of the first to fourth modes, whichcontains the clay mineral in an amount of at least 30 wt. % as solidcontent, the gypsum series in an amount of at least 25 wt. % as solidcontent, and the mineral having a pore size greater than that of thegypsum series in an amount of 30 wt. % or less as solid content.

According to the fifth mode, the form of the deodorizing article issatisfactorily maintained, an excellent balance can be attained betweenadsorption and desorption, and mechanical strength is enhanced.

A sixth mode of the present invention is drawn to a specific embodimentof the deodorizing article of any of the first to fifth modes, whereinthe white inorganic filler is at least one species selected fromcolloidal silica and cement.

According to the sixth mode, mechanical strength is enhanced bycolloidal silica or cement, without lowering the semi-permanentdeodorization effect on the basis of adsorption and desorption of anodor substance.

A seventh mode of the present invention is drawn to a specificembodiment of the deodorizing article of the sixth mode, wherein thewhite inorganic filler is colloidal silica and is contained in an amountof 10 to 20 wt. % as solid content.

According to the seventh mode, mechanical strength is effectivelyenhanced by colloidal silica, without lowering the semi-permanentdeodorization effect on the basis of adsorption and desorption of anodor substance.

An eighth mode of the present invention is drawn to a specificembodiment of the deodorizing article of the sixth mode, wherein thewhite inorganic filler is cement and is contained in an amount of 14 to37 wt. % as solid content.

According to the eighth mode, mechanical strength is effectivelyenhanced by cement, without lowering the semi-permanent deodorizationeffect on the basis of adsorption and desorption of an odor substance.

A ninth mode of the present invention is drawn to a specific embodimentof the deodorizing article of any of the first to eighth modes, which ismolded through slip cast molding.

According to the ninth mode, a favorable dispersion state of the claymineral in the gypsum series is maintained during slip cast molding, andthe mechanical strength required for usual use can be ensured.

A tenth mode of the present invention is drawn to a specific embodimentof the deodorizing article of any of the first to ninth modes, which is,in use, provided in an exhaust system connected to a kitchen.

According to the tenth mode, an offensive odor such as an oil-relatedodor generated in a kitchen is reduced to a certain level or lower.

An eleventh mode of the present invention is drawn to a specificembodiment of the deodorizing article of the tenth mode, which has ahollow cylindrical or columnar form and has a plurality of flow linespenetrated in an axial direction.

According to the eleventh mode, the deodorizing article has such amechanical strength that will not permit collapsing of the articleduring manual handling upon operations such as installation of thearticle in a duct line.

A twelfth mode of the present invention is directed to a method forproducing a deodorizing article, characterized in that the methodcomprises the steps of dispersing in water a clay mineral havingmeso-pores, gypsum series, a mineral having a pore size greater thanthat of the gypsum series, and a white inorganic filler, to thereby forma dispersion; charging the dispersion into a mold through slip casting,and drying the dispersion and releasing the dried product from the mold.

According to the twelfth mode, a deodorizing article having a mechanicalstrength enhanced by the white inorganic filler is produced while asemi-permanent deodorization effect is maintained, the effect beingexerted by the meso-pores of the clay mineral on the basis of adsorptionand desorption of an odor substance, in cooperation with themoisture-maintenance effect of the gypsum series.

A thirteenth mode of the present invention is drawn to a specificembodiment of the method for producing a deodorizing article of thetwelfth mode, wherein the step of dispersing the members in water tothereby form a dispersion further includes dispersing a finely dividedpowder of a clay mineral having meso-pores.

According to the thirteenth mode, a state in which each raw material isuniformly dispersed is consistently attained, thereby producing desireddeodorizing articles having no variation in performance.

A fourteenth mode of the present invention is drawn to a specificembodiment of the method for producing a deodorizing article of thetwelfth or thirteenth mode, which further includes a step of preliminaryfiring at a predetermined temperature the clay mineral havingmeso-pores.

According to the fourteenth mode, the clay mineral that has beensubjected to preliminary firing is dispersed in the gypsum series, andthe resultant mixture is molded. Thus, the meso-pores of the claymineral function effectively, to thereby provide a deodorizing articleexhibiting excellent deodorization performance and mechanical strength.

A fifteenth mode of the present invention is drawn to a specificembodiment of the method for producing a deodorizing article of any ofthe twelfth to fourteenth modes, wherein the clay mineral is at leastone species selected from sepiolite and palygorskite, and the mineralhaving a pore size greater than that of the gypsum series is expandedperlite.

According to the fifteenth mode, there is produced a deodorizing articlewhich exhibits an excellent balance between adsorption and desorptionmaintained by sepiolite or palygorskite and perlite, and which hassatisfactory mechanical strength.

A sixteenth mode of the present invention is drawn to a specificembodiment of the method for producing a deodorizing article of any ofthe twelfth to fifteenth modes, wherein the deodorizing article containsthe clay mineral in an amount of at least 30 wt. % as solid content, thegypsum series in an amount of at least 25 wt. % as solid content, andthe mineral having a pore size greater than that of the gypsum series inan amount of 30 wt. % or less as solid content.

According to the sixteenth mode, there is produced a deodorizing articlewhich exhibits an excellent balance between adsorption and desorptionand satisfactory mechanical strength, and the form of the deodorizingarticle is satisfactorily maintained.

A seventeenth mode of the present invention is drawn to a specificembodiment of the method for producing a deodorizing article of any ofthe twelfth to sixteenth modes, wherein the white inorganic filler is atleast one species selected from colloidal silica and cement.

According to the seventeenth mode, mechanical strength is enhanced bycolloidal silica or cement, without lowering the semi-permanentdeodorization effect on the basis of adsorption and desorption of anodor substance.

An eighteenth mode of the present invention is drawn to a specificembodiment of the method for producing a deodorizing article of theseventeenth mode, wherein the white inorganic filler is colloidal silicaand is contained in an amount of 10 to 20 wt. % as solid content.

According to the eighteenth mode, mechanical strength is effectivelyenhanced by colloidal silica, without lowering the semi-permanentdeodorization effect on the basis of adsorption and desorption of anodor substance.

A nineteenth mode of the present invention is drawn to a specificembodiment of the method for producing a deodorizing article of theseventeenth mode, wherein the white inorganic filler is cement and iscontained in an amount of 14 to 37 wt. % as solid content.

According to the nineteenth mode, mechanical strength is effectivelyenhanced by cement, without lowering the semi-permanent deodorizationeffect on the basis of adsorption and desorption of an odor substance.

The present invention will next be described in detail.

Examples of the clay mineral having meso-pores which may be employed inthe present invention include clay minerals having a tunnel-likemicro-structure such as sepiolite and palygorskite, and synthetic clayminerals such as meso-porous materials (e.g., meso-porous silica andmeso-porous molecular sieve), silica gel, aluminum oxide (alumina), andcarbon aerogel. For example, sepiolite has one-dimensional tunnel pores(i.e., micro-pores) and meso-pores, and more specifically, hasmicro-pores of 0.5 to 1.1 nm originating from the crystal structurethereof, and meso-pores of some tens of nm corresponding tointerparticle spacing.

Such clay minerals are generally known to exert moisture-controllingeffect. According to the present invention, a semi-permanentdeodorization effect on the basis of adsorption and desorption of anodor substance is exerted in cooperation with the moisture-maintenanceeffect of the gypsum series.

No particular limitation is imposed on the particle size of the claymineral. The particle is generally about 0.2 to about 2 mm.

The gypsum series which can be employed in the present invention is acompound which comprises calcium sulfate as a predominant component andcan be molded into a desired shape through reaction with water. Eithernaturally occurring gypsums or chemically synthesized gypsums may beemployed. Examples of the gypsums include crystalline gypsum,hemihydrate, anhydrous gypsum, and plaster of Paris. Generally,commercial plaster of Paris (calcined gypsum) is used.

In the present invention, the clay mineral having meso-pores ispreferably used in an amount of at least 30 wt. % as solid content inorder to attain excellent adsorption performance.

The gypsum series must be used in an amount of at least 25 wt. % assolid content for maintaining the shape of the deodorizing article.Thus, when the deodorizing article is formed from two components, thegypsum series content is preferably 25 to 70 wt. % as solid content.

The aforementioned gypsum series maintains the shape of the deodorizingarticle of the present invention and serves as a water-supply material.Thus, the gypsum series preferably comprises a material which providesmacro-pores of 1 to 10 μm, preferably about 5 μm, after molding thereof.

The deodorizing article of the present invention contains gypsum whichsurrounds sepiolite having micro-pores and meso-pores. The gypsum,having macro-pores of 1 to 10 μm, serves as a water-supply material. Anadsorption-desorption mechanism involving sepiolite and gypsum isconsidered as follows. When an atmosphere or air which passes throughthe deodorizing article contains an odor component at high level,sepiolite adsorbs the odor component which has passed through pores ofgypsum, and in turn transfers water which has been adsorbed by sepioliteto gypsum, to thereby lower the odor level to a certain level or lower.

Even when the odor component does not exist, gypsum continues to adsorbwater until adsorption of water reaches the saturation state. Sepiolite,which exerts moisture-controlling effect, adsorbs water containedtherein. The odor component which has been adsorbed by sepiolite isgradually released through substitution; i.e., competitive adsorption,to thereby lower the odor level to a certain level or lower (i.e.,desorption).

On the basis of the function of water, the deodorizing article of thepresent invention exerts particularly remarkable effect of removing anoil-related odor which is generated in a place such as a kitchen wherevaporization of water is prone to occur during the course of cooking.

As described above, by virtue of the synergistic effect exerted bygypsum series and a clay mineral such as sepiolite, the deodorizingarticle of the present invention adsorbs an odor substance to therebylower the odor level to a certain level or lower, when the target gascontains a large amount of an odor component, and releases the odorcomponent without elevating the level of the released odor component toa certain level or higher, when the odor component level is lowered. Byrepeating the procedure, the odor level can be averaged and lowered to acertain level or lower, with the level being suppressedsemi-permanently.

The deodorizing article of the present invention preferably contains amineral having a pore size greater than that of gypsum series, in viewof promotion of the aforementioned desorption of the odor substance.

Examples of minerals having a pore size greater than that of gypsumseries include expanded perlite (may be referred to as foamed perlite).The expanded perlite, which per se has no adsorption ability, increasesthe entire volume of a mixture of gypsum series and a clay mineralhaving meso-pores when incorporated into the mixture. Since themacro-pore size of the additional mineral is greater than that of gypsumseries, the aforementioned adsorption-desorption is considered to bepromoted.

The amount of the mineral having a large pore size is controlled so asnot lower the relative amounts of active ingredients and so as not togreatly lower overall mechanical strength. Thus, the amount iscontrolled to 30 wt. % or less, preferably 8 to 12.5 wt. % as solidcontent. Although the additional mineral is optional, the mineral ispreferably added in an amount of at least 8 wt. % in order to fullyattain the effect thereof.

No particular limitation is imposed on the particle size of expandedperlite, and the particle size is generally 0.15 to 1 mm.

It is preferred that the deodorizing article of the present inventioncontains a white inorganic filler in order to enhance mechanicalstrength. The white inorganic filler employed herein is an inorganicfiller such as colloidal silica or cement and is capable of enhancingthe mechanical strength of the deodorizing article, without considerablylowering deodorizing performance. It is also preferred that thedeodorizing article of the present invention is molded by dispersing rawmaterials in water to form a dispersion and molding the dispersionthrough slip casting. Thus, preferably, the raw materials enhancemechanical strength of the deodorizing article while favorablemoldability of the dispersion containing the raw materials ismaintained.

From the above viewpoint, the white inorganic filler is preferablyselected from colloidal silica and cement, in consideration of viscosityand pot life of a dispersion containing the filler, enhancement ofmechanical strength, retention of deodorization performance, or otherfactors.

The amount of the white inorganic filler may be determined inconsideration of the aforementioned factors. In general, the amount,which varies depending on the type of the filler employed, is preferablyabout 10 to 20 wt. % as solid content in the case of colloidal silica,and preferably about 14 to 37 wt. % as solid content in the case ofcement. When the amount is less than the lower limit of the aboveranges, enhancement of mechanical strength is insufficiently attained,whereas when the amount exceeds the above ranges, deodorizationperformance becomes poor or handling of a dispersion during molding isconsiderably impaired.

The deodorizing article of the present invention preferably contains afinely divided particle of a clay mineral. The finely divided powder isproduced from a clay mineral having meso-pores, preferably having aparticle size of 75 μm or less, more preferably 45 μm or less. Examplesof such a finely divided powder of a clay mineral include finely dividedsepiolite powder (trade name: Milcon SP-2, product of Showa Mining Co.,Ltd.).

When gypsum series, a clay mineral, a mineral having a pore size greaterthan that of the gypsum series, and a finely divided powder of a claymineral are dispersed in water and the dispersion is poured into a moldthrough slip casting, there can be prevented precipitation of the claymineral and floatation of the mineral having a pore size greater thanthat of the gypsum series, before completion of curing of the gypsumseries. Thus, when a mixture of raw materials contains a finely dividedpowder of a clay mineral, a state in which each raw material isuniformly dispersed is consistently attained during a curing period.Such a stable dispersion state is particularly effective for molding byuse of a mold having a long side length. Accordingly, there can beproduced desired deodorizing articles in which each raw material isuniformly dispersed and which have less variation in performance.

The finely divided powder of a clay mineral exerting the above effect ispreferably contained in an amount of about 0.5 to 3.0 wt. %. When theamount is less than the lower limit, the effect is insufficientlyattained, whereas when the amount in excess of the upper limit,deodorization performance is lowered.

Although some clay minerals exert the same effect, use of a finelydivided powder of a clay mineral having meso-pores, serving as apredominant component of the mixture of raw materials, is preferred soas not to considerably impair, through addition of the clay mineral,deodorization characteristics, inter alia, the desorption effect uponrepeated use of the deodorization article.

The deodorizing article of the present invention is produced by mixingraw materials with dispersion, charging the resultant mixture into amold, and drying the mixture. No particular limitation is imposed on theshape, dimensions, etc. of the deodorizing article. However, since thedeodorization is effected on the basis of adsorption (contact with theodor substance), the deodorizing article preferably has a structureassuring a large contact area. For example, a columnar article or aprismatic article of a honeycomb structure having flow lines penetratedin an axial direction is preferred. A typical hollow cylinder, prism,etc. may also be employed.

No particular limitation is imposed on the method for producing thedeodorizing article of the present invention. After completion of mixingand dispersing raw materials, molding the resultant mixture by dryingcan be performed under the same conditions as employed for yieldingtypical gypsum series products.

However, as mentioned in the Test Examples below, preliminary firing ofsepiolite is preferably performed before mixing and dispersing of rawmaterials. Preliminary firing is considered to prevent crushing orsimilar trouble of sepiolite during mixing and dispersion of rawmaterials, thereby enhancing desorption performance of the moldeddeodorizing article. No particular limitation is imposed on the firingconditions, so long as the aforementioned effect is attained. Forexample, firing is performed at 400 to 800° C. for about one hour.

According to the deodorizing article of the present invention, bendingstrength of the article is enhanced to 0.49 MPa (5 kg/cm²) or higher bythe effect of the white inorganic filler while a semi-permanentdeodorization effect is maintained, the effect being exerted by themeso-pores of the clay mineral on the basis of repeated adsorption anddesorption of an odor substance, in cooperation with themoisture-maintenance effect of the gypsum series. Thus, the deodorizingarticle has such a mechanical strength that will not permit collapsingof the article during ordinary handling such as manual handling.

When a microorganism is caused to adhere to the deodorizing article (themicroorganism being not intentionally caused to adhere during use of thedeodorizing article of the present invention), the microorganismingests, as nutrient, an odor component adsorbed by the deodorizingarticle. In addition, the microorganism produces an enzyme under theconditions satisfying requirements for water content, temperature, etc.

By virtue of enzymatic reaction, an accumulated odor component which hasbeen adsorbed but not desorbed is decomposed, to thereby preventclogging or similar trouble and renew adsorption effect, leading tofurther semi-permanent deodorization performance. Such performanceregeneration effect due to a microorganism is attributed to amicroorganism present in the atmosphere. Thus, the effect is generallyexerted when the deodorizing article is used in the atmosphere.Particularly when the article is used in a kitchen for removing anoil-related odor, an oil-decomposing enzyme such as lipase orlipase-producing bacteria per se may be caused to adhere to the articlein advance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of the deodorizing articleaccording to one embodiment of the present invention.

FIG. 2 is a graph showing the results of Test Example 3 carried out inrelation to the present invention.

FIG. 3 is a graph showing the results of Test Example 4 carried out inrelation to the present invention.

FIG. 4 shows the procedure of Test Example 6 carried out in relation tothe present invention.

FIG. 5 is a graph showing the results of Test Example 6 carried out inrelation to the present invention.

FIG. 6 is a graph showing the results of Test Example 7 carried out inrelation to the present invention.

FIG. 7 is a graph showing the pore size distribution profile obtained inTest Example 8 carried out in relation to the present invention.

FIG. 8 is a graph showing the pore size distribution profile obtained inTest Example 8 carried out in relation to the present invention.

FIG. 9 is a graph showing the pore size distribution profile obtained inTest Example 8 carried out in relation to the present invention.

FIG. 10 is a graph showing the pore size distribution profile obtainedin Test Example 8 carried out in relation to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will next be described in detail by way ofexamples.

EXAMPLE 1

Sepiolite (particle size: 0.5 to 1.0 mm, naturally occurring in Turkey)was subjected to preliminary firing at 600° C. for one hour. Thethus-fired sepiolite, expanded perlite (for example, trade name: TopcoPerlite), finely divided sepiolite powder (trade name: Milcon SP-2,product of Showa Mining Co., Ltd., the <45 μm-particle content: 99.6%),grade-B calcined gypsum, and a white inorganic filler (colloidal silica,Silicadol 20A (solid content 20%), product of Nippon Chemical IndustrialCo., Ltd.) were blended in compositional proportions (parts by weight)shown in Table 1 together (each quantity in parentheses denotes a solidcontent (%); the same convention applies hereafter). Water was added tothe mixture in an amount shown in Table 1. The mixed product was chargedin a mold of a predetermined shape, and dried at 60° C. for 12 hours, tothereby yield a 16-passage deodorizing article 10 as shown in FIG. 1.The deodorizing article 10 had outer dimensions of 10 cm×10 cm×20 cm,and 16 penetrated flow lines 11. Each penetrated flow line 11 wastapered, in consideration of releasing from the mold, and had oneopening (18.7×18.7 mm) having a thickness of a partition wall 12 of 4.8mm and the other opening (17.8×17.8 mm) having a partition wallthickness of 5.6 mm.

EXAMPLE 2

The procedure of Example 1 was repeated, except that alumina cement wasemployed as a white inorganic filler instead of colloidal silica in anamount shown in Table 1, to thereby produce a deodorizing article.

EXAMPLE 3

The procedure of Example 1 was repeated, except that portland cement wasemployed as a white inorganic filler instead of colloidal silica, in anamount shown in Table 1, to thereby produce a deodorizing article.

EXAMPLE 4

The procedure of Example 1 was repeated, except that jet cement(Regulated Set Cement; ultra rapid-hardening cement) was employed as awhite inorganic filler instead of colloidal silica, in an amount shownin Table 1, to thereby produce a deodorizing article.

COMPARATIVE EXAMPLE 1

The procedure of Example 1 was repeated, except that compositionalproportions shown in Table 1 were employed but no white inorganic fillerwas employed, to thereby produce a deodorizing article of ComparativeExample 1.

COMPARATIVE EXAMPLE 2

The procedure of Example 1 was repeated, except that carbon fiber(product of Mitsubishi Rayon Co., Ltd.) was employed instead of a whiteinorganic filler, in an amount shown in Table 1, to thereby produce adeodorizing article of Comparative Example 2.

TEST EXAMPLE 1

In each Example and each Comparative Example, slip casting performanceof a dispersion into a mold, pot life, and time required for removalfrom the mold were determined so as to evaluate handling efficiency. Theresults are shown in Table 1.

TEST EXAMPLE 2

In each Example and each Comparative Example, test samples havingdimensions of 35 mm (width)×70 mm (length)×5 mm (thickness) wereprepared. Bending strength (MPa) of each test sample was determined byuse of a push-pull scale (product of Imada Co., Ltd.) in accordance withJIS K 6911 and the following equation. The results are shown in Table 1,along with molding properties and strength determined in Test Example 1and overall evaluation. Overall evaluation is rated by O (passed bothTest Example 1 and 2) and X (failed to pass at least one of these).Bending strength (MPa)=3PL/2Wt²

-   -   P: Load (N) to cause deflection of a test sample    -   L: Distance between supports (mm)    -   W: Width of a sample (mm)    -   t: Thickness of a sample (mm)

The results of Test Examples 1 and 2 revealed that test samples ofExamples 1 to 4 exhibited molding properties; i.e., handling efficiencynearly equal to that of the test sample of Comparative Example 1containing no white inorganic filler, and a mechanical strength; i.e., abending strength was enhanced to a level higher than 0.49 MPa. The testresults confirmed that mechanical strength was not remarkably enhancedin the sample of Comparative Example 2 containing carbon fiber as areinforcement material, and handling efficiency decreased. Use of glassfiber and use of other inorganic fibers were also confirmed to fail toimprove mechanical strength and handling efficiency. TABLE 1 Ex. 1 Ex. 2Ex. 3 Ex. 4 Comp. Ex. 1 Comp. Ex. 2 Raw Sepiolite 20 20 20 20 20 20materials (39.4%) (35.2%) (35.2%) (35.2%) (49.0%) (48.8%) parts Perlite4 4 4 4 4 4 by weight (7.9%) (7.0%) (7.0%) (7.0%) (9.8%) (9.8%)Sepiolite 0.8 0.8 0.8 0.8 0.8 0.8 fine powder (1.6%) (1.4%) (1.4%)(1.4%) (2.0%) (2.0%) Gypsum 16 16 16 16 16 16 series (31.5%) (28.2%)(28.2%) (28.2%) (39.2%) (39.0%) Colloidal 50 — — — — — silica (19.7%)Cement — 16 16 16 — — (28.2%) (28.2%) (28.2%) Water 11.8 52 52 52 52 52Carbon — — — — — 0.2 fiber (0.5%) Slip casting to mold good*¹ good goodgood good good*¹ Pot life (min) ≅5 ≅15 ≅5 ≅15 ≅15 ≅15 Release time (min)≅45 ≅45 ≅45 ≅45 ≅45 ≅45 Bending strength (MPa) 1.26 0.80 0.69 0.74 0.230.35 Overall evaluation ◯ ◯ ◯ ◯ X XAmount (parts by weight) of raw material in the parentheses represents asolid content.*¹Viscosity slightly higher than that of Comp. Ex. 1

EXAMPLES 5a to 5d

The procedure of Example I was repeated, except that the amount ofcolloidal silica was altered to 12.5 parts by weight, 25 parts byweight, 50 parts by weight, or 75 parts by weight (Examples 5a to 5d) asshown in Table 2, to thereby produce a deodorizing article.

TEST EXAMPLE 3

In a manner similar to that of Test Example 1 or 2, a slip castingperformance of a dispersion into a mold, pot life, time required forremoval from the mold, and bending strength in relation to Examples 5ato 5d were determined. The results are shown in Table 2.

In Examples 5a to 5c, the time-dependent change of viscosity (mPa.s) ofa dispersion after completion of mixing of raw materials was measured.The results are shown in FIG. 2.

The results indicate the following. During slip cast molding, thedispersion preferably has a viscosity of 750 to 1,750 mPa.s, and theviscosity is preferably maintained within the range for a specificperiod of time. When the viscosity of the produced dispersion remainsless than 750 mPa.s for a long time, components contained in thedispersion are settled, in a sequence corresponding to specific gravity,before or after slip casting into a mold, yielding a deodorizing articleof unsatisfactory performance. When the viscosity of the produceddispersion surpasses 1,750 mPa.s in a short period of time, thedispersion entrains air or is poorly charged, due to low mobility duringslip casting into a mold, imposing restrictions on the slip castingoperation. Needless to say, both cases are not preferred. The dispersionof Example 5a, containing colloidal silica at a solid content of 5.8%,provides sufficiently enhanced bending strength. However, raw materialcomponents readily cause separation, and six minutes after preparationof the dispersion, the viscosity, which has an initial value of 750mPa.s, drastically increases. Thus, the dispersion is not suited forpractical use. The dispersion of Example 5d, containing colloidal silicaat a solid content of 26.9%, causes gelation of raw materials, therebyimpairing moldability. The dispersions of Examples 5b and 5c, containingcolloidal silica at solid contents of 10.9% and 19.7%, respectively,provide excellent moldability and enhanced bending strength. TABLE 2 Ex.5a Ex. 5b Ex. 5c Ex. 5d Raw Sepiolite 20 20 20 20 materials (46.2%)(43.7%) (39.4%) (35.8%) parts Perlite 4 4 4 4 by weight (9.2%) (8.7%)(7.9%) (7.2%) Sepiolite 0.8 0.8 0.8 0.8 fine powder (1.8%) (1.7%) (1.6%)(1.4%) Gypsum 16 16 16 16 series (37.0%) (34.9%) (31.5%) (28.7%)Colloidal 12.5 25 50 75 silica (5.8%) (10.9%) (19.7%) (26.9%) Water 4232 11.8 11.8 Slip casting to mold separation good*¹ good*¹ gela-tion Potlife (min) ≅7 ≅7 ≅5 ≅1 Release time (min) ≅45 ≅45 ≅45 ≅45 Bendingstrength (MPa) 0.55 0.80 1.26 0.88 Overall evaluation X ◯ ◯ XAmount (parts by weight) of raw material in the parentheses represents asolid content.*¹Viscosity slightly higher than that of Comp. Ex. 1

EXAMPLES 6a to 6e

The procedure of Example 2 was repeated, except that the amount ofalumina cement was altered to 4 parts by weight, 8 parts by weight, 16parts by weight, 24 parts by weight, or 32 parts by weight (Examples 6ato 6e), to thereby produce a deodorizing article.

TEST EXAMPLE 4

In a manner similar to that of Test Example 1 or 2, a slip castingperformance of a dispersion into a mold, pot life, time required forremoval from the mold, and bending strength in relation to Examples 6ato 6e were determined. The results are shown in Table 3.

In Examples 6c to 6e, the time-dependent change of viscosity (mPa.s) ofa dispersion after completion of mixing of raw materials was measured.The results are shown in FIG. 3.

The results indicate the following. The dispersion of Example 6a,containing alumina cement at a solid content of 8.9%, providesinsufficiently enhanced bending strength. The dispersion of Example 6e,containing alumina cement at a solid content of 44.0%, has highvisicosity, resulting in poor moldability. The dispersions of Example 6bto 6d, containing alumina cement at solid contents of 16.4%, 28.2%, and37.0%, respectively, provide excellent moldability and enhanced bendingstrength. TABLE 3 Ex. 6a Ex. 6b Ex. 6c Ex. 6d Ex. 6e Raw Sepiolite 20 2020 20 20 materials (44.6%) (41.0%) (35.2%) (30.9%) (27.5%) parts Perlite4 4 4 4 4 by weight (8.9%) (8.2%) (7.0%) (6.2%) (5.5%) Sepiolite 0.8 0.80.8 0.8 0.8 fine powder (1.8%) (1.6%) (1.4%) (1.2%) (1.1%) Gypsum 16 1616 16 16 series (35.7%) (32.8%) (28.2%) (24.7%) (22.0%) Alumina 4 8 1624 32 cement (8.9%) (16.4%) (28.2%) (37.0%) (44.0%) Water 52 52 52 52 52Slip casting to mold good good good good viscous Pot life (min) ≅15 ≅15≅15 ≅15 ≅0 Release time ≅45 ≅45 ≅45 ≅45 ≅45 Bending strength (MPa) 0.370.52 0.80 0.82 0.89 Overall evaluation X ◯ ◯ ◯ XAmount (parts by weight) of raw material in the parentheses represents asolid content.

TEST EXAMPLE 5

The procedure of Example 2 was repeated, except that the amount ofalumina cement was changed to 4, 5, 6, 7, 8, 16, or 32 parts by weightas shown in Table 4, to thereby produce a dispersion. The same testsamples as those of Test Example 2 were molded from each dispersion andwere subjected to bending test. The results are shown in Table 4.

The similar bending test was performed, except that portland cement wasemployed instead of alumina cement. The results are also shown in Table4.

The results indicate that incorporation of either alumina cement orportland cement in an amount of 7 parts by weight (solid content: 14.6%)leads to a bending strength sufficient for install operation. TABLE 4Formulation Bending strength (MPa) (parts by weight) Alumina cementPortland cement 4 0.37 0.39 5 0.44 0.45 6 0.47 0.47 7 0.50 0.54 8 0.520.59 16 0.80 0.69 32 0.89 0.70

TEST EXAMPLE 6

The deodorizing article of Example 6b was pulverized, to thereby providetest samples. Each sample was subjected to an oil-related gas adsorptionand desorption repeating test in the following manner. FIG. 4 shows theprocedure of the test.

(1) A sample obtained from the deodorizing article (see FIG. 1) wasdried in an atmosphere at about 50° C. for 24 hours (preliminarytreatment), after which the dried sample was allowed to stand in a50%-RH atmosphere at about 20° C. for 24 hours.

(2) Oil 23 was added to a frying pan 22 placed in a chamber 21 andheated so as to generate oil-related gas. The gas present in the chamber21 was sucked into a 20-L sampling bag 24 (hereinafter referred tosimply as “bag”) by means of a pump 25 (FIG. 4(a)).

(3) The gas concentration contained in the bag 24 was controlled to 20to 25 ppm (CH₄).

(4) A test sample 10A (2 g) was charged into a sample tube 26. One endof the sample tube was connected to the bag 24, and the other end of thesample tube was connected to a pump 28 via a flow meter 27.

(5) By operating the pump 28, the oil-related gas contained in the bag24 was fed at 0.5 L/min into the sample tube 26. The gas was sampledevery one minute for 31 minutes at an inlet sampling position 31(upstream with respect to the sampling tube 26) and an outlet samplingposition 32 (downstream with respect to the sampling tube 26) (FIG.4(b)).

(6) Each gas sample was analyzed by means of a total hydrocarbon meter(detection limit: 0.1 ppm CH₄), and the amount of adsorbed gas componentwas calculated by integrating the difference in gas level between theinlet sampling potion and the outlet sampling position.

(7) The bag 24 was removed from the sample tube 26, and a silica geltrap 35 was connected to the sample tube 26 via an activated carbon trap36. Air which had been passed through silica gel and activated carbonwas fed to the sample tube 26 at 0.5 L/min for 15 minutes, to therebyeffect desorption of the adsorbed gas component from the test sample 10Acharged in the sample tube 26 (FIG. 4(c)).

(8) The sample tube 26 was removed and allowed to stand at 32° C. fortwo days.

(9) The procedure including steps (2) to (8) was repeated.

A test sample which had been subjected to the above procedure is denotedby “Ex. 6b sample” (microorganism-related). A test sample which had beensubjected to a similar procedure, except that a membrane filter forremoving microorganisms was provided on the upstream side of the testsample during desorption step (7), is denoted by “Ex. 6b-1 sample”(adsorption/desorption). A test sample which had been subjected to asimilar procedure, except that the desorption step (7) was omitted, isdenoted by “Ex. 6b-2 sample” (adsorption only).

The results are shown in FIG. 5. The results indicate that as comparedwith Ex. 6b sample, the adsorption effect of the deodorizing article(Ex. 6b-1 sample) decreases as the steps are performed repeatedly. Thedecrease in adsorption effect may be attributed to failure to attainmicrobial effect. Ex. 6b-2 sample which had not been subjected to anydesorption step exhibited further decreased adsorption effect. Thus,these results confirm that the deodorizing article of the presentinvention releases an adsorbed odor component and that the adsorptioneffect is renewed and maintained for a long period of time by virtue ofmicrobial effect.

TEST EXAMPLE 7

Test Example 7 was carried out in a manner similar to that of TestExample 6 employing the deodorizing article of Example 6b. After theadsorption step had been performed for 31 minutes, the outlet odorconcentration of the gas was determined at every one minute whiledesorption was performed. The results are shown in FIG. 6.

The results indicate that the odor substance adsorbed over about 30minutes was nearly completely released for 60 minutes.

TEST EXAMPLE 8

The pore size distribution profile of Ex. 1 sample containing colloidalsilica at a solid content of 19.7%, that of Ex. 6b sample containingalumina cement at a solid content of 16.4%, and that of Ex. 6c samplecontaining alumina cement at a solid content of 28.2% were obtainedthrough the mercury penetration method, and these profiles were comparedwith the profile of Comparative Example 1. The pore size distributionprofiles are shown in FIGS. 7 to 10. Porosity (%) values derived fromthese profiles are shown in Table 5.

The results indicate that the deodorizing articles of Examples 1, 6b,and 6c and Comparative Example 1 have a pore size peak falling within arange of 1 μm to 10 μm and a porosity corresponding to each distributionprofile. Thus, the deodorizing articles of the Examples were confirmedto have an enhanced mechanical strength while deodorization performanceis maintained. TABLE 5 Porosity (%) Example 1 65.8 Example 6b 60.0Example 6c 59.5 Comparative Example 1 56.9

INDUSTRIAL APPLICABILITY

As described hereinabove, by virtue of synergistic effect exerted bygypsum series and a clay mineral having meso-pores such as sepiolite orsynergistic effect exerted through addition of a mineral havingmacro-pores of a pore size greater than that of the gypsum series (e.g.,perlite), the deodorizing article of the present invention adsorbs anodor substance to thereby lower the odor level to a certain level orlower, when the target gas contains a large amount of an odor component,and releases the odor component without elevating the level of thereleased odor component to a certain level or higher, when the odorcomponent level is lowered. By repeating the procedure, the odor levelcan be averaged and lowered to a certain level or lower, with the levelbeing suppressed semi-permanently. In addition, by virtue of the whiteinorganic filler incorporated in the article, a mechanical strength suchthat the deodorizing article cannot readily collapsed during routineoperation is attained.

1. A deodorizing article, characterized in that the deodorizing articleis produced by dispersing in a medium a clay mineral having meso-pores,gypsum series, a mineral having a pore size greater than that of thegypsum series, and a white inorganic filler, and molding the formeddispersion.
 2. A deodorizing article according to claim 1, which furthercontains a finely divided powder of a clay mineral having meso-pores. 3.A deodorizing article according to claim 1 or 2, which has a bendingstrength of 0.49 MPa or higher.
 4. A deodorizing article according toany of claims 1 to 3, wherein the clay mineral is at least one speciesselected from sepiolite and palygorskite, and the mineral having a poresize greater than that of the gypsum series is expanded perlite.
 5. Adeodorizing article according to any of claims 1 to 4, which containsthe clay mineral in an amount of at least 30 wt. % as solid content, thegypsum series in an amount of at least 25 wt. % as solid content, andthe mineral having a pore size greater than that of the gypsum series inan amount of 30 wt. % or less as solid content.
 6. A deodorizing articleof any of claims 1 to 5, wherein the white inorganic filler is at leastone species selected from colloidal silica and cement.
 7. A deodorizingarticle according to claim 6, wherein the white inorganic filler iscolloidal silica and is contained in an amount of 10 to 20 wt. % assolid content.
 8. A deodorizing article according to claim 6, whereinthe white inorganic filler is cement and is contained in an amount of 14to 37 wt. % as solid content.
 9. A deodorizing article according to anyof claims 1 to 8, which is molded through slip cast molding.
 10. Adeodorizing article according to any of claims 1 to 9, which is to beused in an exhaust system connected to a kitchen.
 11. A deodorizingarticle according to claim 10, which has a hollow cylindrical orcolumnar form and has a plurality of flow lines penetrated in an axialdirection.
 12. A method for producing a deodorizing article,characterized in that the method comprises the steps of dispersing inwater a clay mineral having meso-pores, gypsum series, a mineral havinga pore size greater than that of the gypsum series, and a whiteinorganic filler, to thereby form a dispersion; charging the dispersioninto a mold through slip casting, and drying the dispersion andreleasing the dried product from the mold.
 13. A method for producing adeodorizing article according to claim 12, wherein the step ofdispersing the members in water to thereby form a dispersion furtherincludes dispersing a finely divided powder of a clay mineral havingmeso-pores.
 14. A method for producing a deodorizing article accordingto claim 12 or 13, which further includes a step of preliminary firingthe clay mineral having meso-pores at a predetermined temperature.
 15. Amethod for producing a deodorizing article according to any of claims 12to 14, wherein the clay mineral is at least one species selected fromsepiolite and palygorskite, and the mineral having a pore size greaterthan that of the gypsum series is expanded perlite.
 16. A method forproducing a deodorizing article according to any of claims 12 to 15,wherein the deodorizing article contains the clay mineral in an amountof at least 30 wt. % as solid content, the gypsum series in an amount ofat least 25 wt. % as solid content, and the mineral having a pore sizegreater than that of the gypsum series in an amount of 30 wt. % or lessas solid content.
 17. A method for producing a deodorizing articleaccording to any of claims 12 to 16, wherein the white inorganic filleris at least one species selected from colloidal silica and cement.
 18. Amethod for producing a deodorizing article according to claim 17,wherein the white inorganic filler is colloidal silica and is containedin an amount of 10 to 20 wt. % as solid content.
 19. A method forproducing a deodorizing article according to claim 17, wherein the whiteinorganic filler is cement and is contained in an amount of 14 to 37 wt.% as solid content.